History has shown that a power vacuum on the Korean Peninsula is an invitation to aggression. The 60-year-period from the Sino-Japanese War of 1894-95 to the end of the Korean War stands in marked contrast to the 60-year-period of de facto peace since 1953. In the former, four major wars enveloped Korea and its vicinity, including the Russo-Japanese War of 1904-05 and the Second Sino-Japanese War. In the latter, the balance of power has been maintained primarily by virtue of the U.S.-ROK alliance, albeit at the cost of periodic lethal attacks and threats from North Korea. This chapter addresses the historical lessons of power shift in Northeast Asia for contemporary international politics and the strategic implications of South Korea’s embrace of China and its seeming inability to overcome, in Korean parlance, “issues of the past” with Japan.